In a series of 2n observations, half of them are equal to 'a' and the remaining half are equal to '-a'. By adding a constant 'b' to each of these observations, the mean and standard deviation of the new set become 5 and 20 respectively. Then the value of a2 + b2 is equal to:

In a moderately skewed distribution, if Mean = 12 and Median = 8, then using Empirical relation (Mode = 3 Median - 2 Mean), what is the value of Mode?

If 4y - 5x = 15 is the regression line of y on x and the coefficient of correlation between x and y is 0.75, what is the value of the regression coefficient of x on y (bxy)?